Characterizing a Major Urban Stream Restoration Project: Nine Mile Run (Pittsburgh,Pennsylvania, USA)

Urban stream restoration continues to be used as an ecological management tool, despite uncertainty about the long‐term sustainability and resilience of restored systems. Evaluations of restoration success often focus on specific instream indicators, with limited attention to the wider basin or parallel hydrologic and geomorphic process. A comprehensive understanding of urban stream restoration progress is particularly important for comparisons with nonurban sites as urban streams can provide substantial secondary benefits to urban residents. Here, we utilize a wide range of indicators to retrospectively examine the restoration of Nine Mile Run, a multi‐million dollar stream restoration project in eastern Pittsburgh (Pennsylvania, USA). Examination of available continuous hydrological data illustrates the high cost of failures to incorporate the data into planning and adaptive management. For example, persistent extreme flows drive geomorphic degradation threatening to reverse hydrologic connections created by the restoration and impact the improved instream biotic communities. In addition, human activities associated with restoration efforts suggest a positive feedback as the stream restoration has focused effort on the basin beyond the reach. Ultimately, urban stream restoration remains a potentially useful management tool, but continued improvements in post‐project assessment should include examination of a wider range of indicators.     

Microbial community composition and function across an arctic tundra landscape

Arctic landscapes are characterized by a diversity of ecosystems, which differ in plant species composition, litter biochemistry, and biogeochemical cycling rates. Tundra ecosystems differing in plant composition should contain compositionally and functionally distinct microbial communities that differentially transform dissolved organic matter as it moves downslope from dry, upland to wet, lowland tundra. To test this idea, we studied soil microbial communities in upland tussock, stream-side birch-willow, and lakeside wet sedge tundra in arctic Alaska, USA. These are a series of ecosystems that differ in topographic position, plant composition, and soil drainage. Phospholipid fatty acid (PLFA) analyses, coupled with compound-specific 13C isotope tracing, were used to quantify microbial community composition and function; we also assayed the activity of extracellular enzymes involved in cellulose, chitin, and lignin degradation. Surface soil from each tundra ecosystem was labeled with 13C-cellobiose,13C-N-acetylglucosamine, or 13C-vanillin. After a five-day incubation, we followed the movement of 13C into bacterial and fungal PLFAs, microbial respiration, dissolved organic carbon, and soil organic matter. Microbial community composition and function were distinct among tundra ecosystems, with tussock tundra containing a significantly greater abundance and activity of soil fungi. Although the majority of 13C-labeled substrates rapidly moved into soil organic matter in all tundra soils (i.e., 50-90% of applied 13C), microbial respiration of labeled substrates in wet sedge tundra soil was lower than in tussock and birch-willow tundra; approximately 8% of 13C-cellobiose and approximately 5% of 13C-vanillin was respired in wet sedge soil vs. 26-38% of 13C-cellobiose and 18-21% of 13C-vanillin in the other tundra ecosystems. Despite these differences, wet sedge tundra exhibited the greatest extracellular enzyme activity. Topographic variation in plant litter biochemistry and soil drainage shape the metabolic capability of soil microbial communities, which, in turn, influence the chemical composition of dissolved organic matter across the arctic tundra landscape.     

Book reviews

ANALYTICAL PLANNING: THE ORGANISATION OF SYSTEMS

Thomas L. Saaty and Kevin P. Kearns

Pergamon Press, 1985. Price: U.S. $40.00, U.K. £29.50.

THE GEOGRAPHER AT WORK

Peter Gould

Routledge and Kegan Paul, London 1985’ Price: £8.95.

UTOPIA ON TRIAL

Alice Colman

Hilary Shipman Ltd., 19 Framfield Road, Highbury, London. May 1985 (reprinted August, 1985). Price: £7.95.

SIR RAYMOND UNWIN: ARCHITECT, PLANNER AND VISIONARY

Frank Jackson

A. Zwemmer Ltd., London 1985. 187 pp. with maps and illustrations.

STRATEGIC PLANNING IN ACTION: THE IMPACT OF THE CLYDE VALLEY REGIONAL PLAN 1946–1982

R. Smith and U. Wannop (eds)

Gower, 1985, 272 pp. Price: £16.50.

LOCALITIES, CLASS AND GENDER

The Lancaster Regionalism Group (Linda Murgatroyd, Mike Savage, Dan Shapiro, John Urry, Sylvia Walby, Alan Warde, with Jane Mark‐Lawson)

Pion Ltd., 1985. Price: £12.00.     

Ecosystem Service Restoration after 10 Years of Rewetting Peatlands in NE Germany

The restoration of ecosystem services, i.e., production, regulation, and information, is a global challenge, which the federal state of Mecklenburg-Vorpommern in NE Germany addressed in 2000 by rewetting over 20,000 ha of degraded peatlands within the Mire Restoration Program. We evaluated ecosystem services in 23 rewetted sites by assessing the following mire parameters within a ten year period: (a) dominant vegetation at the ecosystem level, (b) peat formation potential at the landscape level, and (c) aboveground biomass and nutrient levels. Seven to 10 years after rewetting, the wetlands formed a mosaic of vegetation types with the highest potential for peat formation and several dominant, peat-forming species accumulated high levels of aboveground biomass and nutrients (C, N, P). Common reed (Phragmites australis) accumulated the most biomass (up to 24 t dry matter/ha), and N+P during the growing season. A future management option is to annually harvest aquatic and wetland plants to reduce nutrient levels in restored mire ecosystems.     

Nitrogen turnover in the leaf litter and fine roots of sugar maple

In order to better understand the nitrogen (N) cycle, a pulse of 15NO3- was applied in 1998 to a sugar maple (Acer saccharum) dominated northern hardwood forest receiving long-term (1994-2008) simulated atmospheric N deposition. Sugar maple leaf litter and live fine-root 15N were quantified for four years prior to labeling and for 11 subsequent years. Continuous sampling of 15N following addition of the tracer enabled calculation of leaf litter and fine-root N pool turnover utilizing an exponential decay function. Fine-root 15N recovery peaked at 3.7% +/- 1.7% the year the tracer was applied, while leaf litter 15N recovery peaked in the two years following tracer application at approximately 8%. These results suggest shoots are primarily constructed from N taken up in previous years, while fine roots are constructed from new N. The residence time of N was 6.5 years in leaf litter and 3.1 years in fine roots. The longer residence time and higher recovery rate are evidence that leaves were a stronger sink for labeled N than fine roots, but the relatively short residence time of tracer N in both pools suggests that there is not tight intra-ecosystem cycling of N in this mature forest.     

Conservation at landscape level: A strategy for survival: The role of research

Summary The objectives, appropriate strategies, the state of conservation in South Africa, and the contributed research which is needed, are evaluated. It is suggested that the ultimate objectives of conservation are to maintain the ecosystem to support people and to achieve economic advantages. These can only be obtained by providing for the greatest possible diversity of life on Earth. An appropriate conservation strategy can be based on a balanced combination of five types of conservation opportunities. These opportunities are: (i) formal conservation in reserves, (ii) promotion of land use change for conservation, (iii) law enforcement, (iv) national resource utilisation planning, and (v) the development of a national land ethic. Adjustment of the opportunity combination to address changing threast must be an ongoing exercise. Conservation strategies need to be based on sound conceptual models of ecosystem structure and function, as well as human needs and aspirations. The main goals of the conservation ecologist are the development, testing and validation of conceptual models of ecosystems.Mr Zak Le Roux is employed in the Scientific Services Section of the Ecosystem Conservation Department of the Natal Parks Board. He possesses a BSc in Forestry and Nature Conservation from the University of Stellenbosch, and is currently undertaking research in Plant Ecology at the University of Natal. A tenth generation South African, his work focuses on vegetation dynamics of semi-arid savanna landscapes and general conservation in Zululand. In particular, this involves the integration of wildlife with agriculture, and the development of more appropriate land uses in the areas surrounding the parks.     

BIOGEOCHEMICAL EFFECTS OF GLOBAL CHANGE ON U.S. NATIONAL PARKS1

ABSTRACT: Federal parks and other public lands have unique mandates and rules regulating their use and conservation. Because of variation in their response to local, regional, and global‐scale disturbance, development of mitigation strategies requires substantial research in the context of long‐term inventory and monitoring. In 1982, the National Park Service began long‐term, watershed‐level studies in a series of national parks. The objective was to provide a more comprehensive database against which the effects of global change and other issues could be quantified. A subset of five sites in North Carolina, Texas, Washington, Michigan, and Alaska, is examined here. During the last 50 years, temperatures have declined at the southern sites and increased at the northern sites with the greatest increase in Alaska. Only the most southern site has shown an increase in precipitation amount. The net effect of these trends, especially for the most northern and southern sites, would likely be an increase in the growing season and especially the time soil processes could continue without moisture or temperature limitations. During the last 18 years, there were few trends in atmospheric ion inputs. The most evident was the decline in SO₄² deposition. There were no significant relationships between ion input and stream water output. This finding suggests other factors as modification of precipitation or canopy throughfall by soil processes, hydrologic flow path, and snowmelt rates are major processes regulating stream water chemical outputs.     

Atmospheric Emissions from Oxidation Ponds

The electrodes in industrial precipitators collect many tons of dust daily, and the efficient transfer of this dust burden to the hoppers is a challenging problem in mechanical engineering. Many varieties of devices have been tried; hammers, vibrators, scrapers, water flushing, gas blasting, etc. Impact devices for this purpose are usually called “rappers.” Laboratory experiments described in this paper show that normal (perpendicular) rapping is more effective than shear rapping; that thick dust layers are more easily removed by rapping than thin ones; that rapping becomes easier with increasing temperature, within limits; and that the electrostatic forces acting upon the precipitated dust layer play an important role. Quantitative data are shown graphically. The relation of these results to previous studies by other investigators is discussed.